1. Angelina Zhuravleva Team «Izolenta»
The task №6 Apples
Angelina Zhuravleva
Team «Izolenta»

2. Our team:
- Polina Parinova(captain) -Angelina Zhuravleva - Ilia Vasiliev -Sergey Glebov -Maksim Shilihin -Elisaveta Zarezina

3. Task
Why do apple slices turn brown after being cut? Investigate the speed of this process and test methods to prevent browning of apple slices.

4. The structure of research:
Aim:
Investigate the process of browning after apple is being cut.
Our objectives:
Provide methods to prevent browning.
Investigate the speed of this process.
Сonduct experiments.
Make the full conclusion.

5. The polyphenols contained in the Apple

6. The reason of turn brown
PPO catalyzes reactions where molecular oxygen is the acceptor of hydrogen , and phenols act as a donor of hydrogen. The result is ortho-benzoquinone. It contains an unique system of paired connections called Qinode group. Qinode group is chromophore. ortho-benzoquinone is painted in bright red color due to the longer conjugated system, causing bathochromic shift.
PPO

7. Factors that determine the rate of darkening
1.PPO activity pH
Temperature
Presence of inhibitor
2. Oxygen

8. PPO Active: 5-7 pH Temperature: 10-60°C
Belongs to the class of oxidoreductases.
The main characteristic is ability to catalyze two reactions:
hydroxylation of o-phenols To O-difenol
oxidation by molecular oxygen in difenol quinones
Active:
5-7 pH
Temperature: 10-60°C

9. KOH
HCl
NaCl
C6H8O7
CH₃COOH
10 minute
170 minute
330 minute

10. Tirosinasa
DOPA
Decarboksilasa
Dopamin

11. The formation of melanin
KOH
The formation of melanin
Eymelanin
Dopamine
Katehol-melanin
Katehol

12. HCl
Protein denaturation
Formation of chlorohydroquinone

13. C6H8O7
The antioxidant molecules interact with the active radicals with the formation of inactive radicals. →
[O] + +

14. Stop air penetration

15. Blanching

16. Inhibitor
Diethylcarbamoyl

17. β-cyclodextrin (heptamer of glucose)

19. D’ =Dn+1 – Dn / t2 – t1 => D’=0,00005 unit of optical density/ second

20. Calculations I/I’=T D’ =Dn+1 – Dn / t2 – t1 I - transmitted ray
I҆ - incident ray
T – coefficient of transmittance
D=lgT
D’ =Dn+1 – Dn / t2 – t1
D’- the speed of change of optical density.
From Dn to Dn+1 - line section

21. Conclusion
The result of oxidation is ortho-benzoquinone. It is painted in red color because of the longer conjugated system.
Melanin is formed (when pH>7)
The ways to stop browning: decrease of pH; stopping air penetration; inhibitor; blanching; penetration of antioxidants.
We investigated the speed of this process.
D’=0,00005 unit of optical density/ second.

22. Thank you for watching!

23. Used saucers http://flavorchemist.livejournal.com/165771.html

24. A diamine is an organic compound with two amino groups.